fix(ci): split PR workflow into two to handle events separately

.github/workflows/pr-change-set.yaml

@@ -0,0 +1,26 @@
+# This workflow checks and tests the package code, and it builds all package
+# artifacts whenever there were changes to a pull request.
+
+name: 'Pull Request: change set'
+on:
+  pull_request:
+    branches:
+    - main
+    - staging
+    types:
+    - opened
+    - reopened
+    - synchronize
+permissions:
+  contents: read
+
+jobs:
+
+  # If the build workflow needs to access secrets, they need to be passed using `secrets: inherit`.
+  # See https://docs.github.com/en/actions/using-workflows/reusing-workflows to learn more.
+  # See  https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions
+  # for the security recommendations.
+  build:
+    uses: ./.github/workflows/build.yaml
+    permissions:
+      contents: read

.github/workflows/pull-request.yaml → .github/workflows/pr-conventional-commits.yaml

@@ -3,7 +3,7 @@
 # tool to check the title of the PR and all commit messages of the branch
 # which triggers this Action.
 
-name: Pull Request
+name: 'Pull Request: conventional commits'
 on:
   pull_request:
     branches:
@@ -19,7 +19,6 @@ permissions:
 
 jobs:
   conventional-commits:
-    name: Check PR title and commit messages
     runs-on: ubuntu-latest
     steps:
 
@@ -55,10 +54,3 @@ jobs:
         PR_BASE_REF: ${{ github.event.pull_request.base.ref }}
         PR_HEAD_REF: ${{ github.event.pull_request.head.ref }}
         PR_HEAD_REPO_CLONE_URL: ${{ github.event.pull_request.head.repo.clone_url }}
-
-  build:
-    needs: conventional-commits
-    if: ${{ github.event.action != 'edited' }}
-    uses: ./.github/workflows/build.yaml
-    permissions:
-      contents: read